A sulfur recovery plant is commercially used including a sulfur purifier which cools gaseous sulfur so as to condensate to produce liquid sulfur while removing impurities contained therein. Such gaseous sulfur is, for example, produced from hydrogen sulfide formed as a by-product in a hydrodesulfurization plant or a synthetic gas production plant. Such sulfur recovery plant includes a regenerated sulfur recovery apparatus which recovers sulfur as reusable regenerated sulfur while melting solid sulfur depositing onto an inner wall of the sulfur purifier. FIG. 3 schematically shows a flow sheet of the regenerated sulfur recovery apparatus 200 of the prior art.
A sulfur recovery plant 201 includes a regenerated sulfur recovery apparatus 200, a sulfur gas production apparatus (not shown), a sulfur purifier 210, and a sulfur recovery tank (not shown). The sulfur production apparatus burns sulfur sulfide (H2S) as a raw material so as to form sulfur dioxide (SO2), and reacts sulfur dioxide and hydrogen sulfide so as to form gaseous sulfur.
The sulfur purifier 210 and the sulfur recovery tank are used to recover the gaseous sulfur in the state of liquid which sulfur is produced in the sulfur production apparatus. The sulfur purifier 210 is controlled to keep its inside temperature at a temperature which is a little higher than a solidification temperature of sulfur (for example, 130° C. to 150° C.). The gaseous sulfur having been supplied into the sulfur purifier 210 through a sulfur gas supply line 213 when a sulfur gas supply line valve 212 is opened is formed into liquid droplets. At this stage, the liquid droplets contact with an adsorbent in the sulfur purifier 210, so that impurities (such as chlorine, ammonia and so on) contained in the liquid droplets are removed by means of the adsorption, and liquid sulfur produced through the condensation is discharged while passing through a liquid sulfur discharge line 215 when a discharge line valve 214 is opened. The liquid sulfur thus discharged from the sulfur purifier 210 is recovered in a sulfur recovery tank.
The regenerated sulfur recovery apparatus 200 melts solid sulfur deposited onto an inner wall of the sulfur purifier 210 and recovers such molten sulfur as regenerated sulfur which is able to be reused. The regenerated sulfur recovery apparatus 200 comprises a steam supply means 218, a molten sulfur reservoir 220 and a regenerated sulfur recovery tank 230.
A steam supply means 218 supplies steam at a temperature of about 150° C. into the sulfur purifier 210 through a steam supply line 217 when a steam supply line valve 216 is opened, so that the solid sulfur deposited onto the inner wall of the sulfur purifier 210 is melted. Thus molten sulfur passes through a molten sulfur flowing line 223 when a flowing line valve 222 is opened, and it is recovered and stored by the molten sulfur reservoir 220. The molten sulfur stored in the molten sulfur reservoir 220 contains much water derived from the steam supplied by the steam supply means 218, and such water contained in the molten sulfur is converted to steam when the molten sulfur reservoir 220 is heated by a reservoir heating means 221. Such steam is exhausted to the outside of the reservoir through an exhaust gas line 241 together with an exhaust gas such as hydrogen sulfide, and then subjected to a detoxification treatment in an exhaust gas detoxification apparatus 240.